Internal assessment resource Science 1.12B v3 for Achievement Standard 90951
PAGE FOR TEACHER USE
NZQA
Approved
Internal Assessment Resource
Science Level 1
This resource supports assessment against:
Achievement Standard 90951 version 3
Investigate the biological impact of an event on a New Zealand
ecosystem
Resource title: Freshwater Ecosystem
4 credits
This resource:

Clarifies the requirements of the standard

Supports good assessment practice

Should be subjected to the school’s usual assessment quality assurance
process

Should be modified to make the context relevant to students in their school
environment and ensure that submitted evidence is authentic
Date version published by
Ministry of Education
February 2015 Version 3
Quality assurance status
These materials have been quality assured by NZQA.
To support internal assessment from 2015
NZQA Approved number A-A-02-2015-90951-02-4582
Authenticity of evidence
Teachers must manage authenticity for any assessment
from a public source, because students may have
access to the assessment schedule or student exemplar
material.
Using this assessment resource without modification
may mean that students’ work is not authentic. The
teacher may need to change figures, measurements or
data sources or set a different context or topic to be
investigated or a different text to read or perform.
This resource is copyright © Crown 2015
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Internal assessment resource Science 1.12B v3 for Achievement Standard 90951
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Internal Assessment Resource
Achievement Standard Science 90951: Investigate the biological
impact of an event on a New Zealand ecosystem
Resource reference: Science 1.12B v3
Resource title: Freshwater Ecosystem
Credits: 4
Teacher guidelines
The following guidelines are supplied to enable teachers to carry out valid and
consistent assessment using this internal assessment resource.
Teachers need to be very familiar with the outcome being assessed by Achievement
Standard Science 90951. The Achievement Criteria and the Explanatory Notes
contain information, definitions, and requirements that are crucial when interpreting
the standard and assessing students against it.
Context/setting
Before using this task, you need to select, finalise, or negotiate a context that will
engage your students, and adapt the activity to suit the context. Create or finalise any
student pages that are needed, and ensure that the assessment schedule aligns with
the task in its final form.
The task in its current form requires students to carry out field investigations in two
areas of a freshwater ecosystem with different environmental factors that result from
a human impact such as urbanisation or pollution. The two areas could include:

an urban area and a rural area

an urban stream in a residential area and one in an industrial area.
Students will investigate the freshwater ecosystem and identify the human impact
they intend to study. This will help them determine the factors involved and the data
they should collect.
Students will collect data from two areas of the freshwater ecosystem. One of these
will show significant change(s) that result from a human impact such as pollution or
urbanisation. The second area will be relatively unaffected to enable comparison
between the two and consideration of the effect of the human impact or event on the
organisms within the ecosystem.
The choice of sites is important. Students must be able to discuss meaningful
changes in environmental factors and the effects of the human impact on the
ecosystem.
Students need to use a sampling system that enables them to compare data
collected at the two different sites. Sampling techniques are provided in this task, but
students could use alternative means of data collection, with direction from the
teacher.
The intent of this activity is that students will collect, collate, and process at least one
set of field data from the freshwater ecosystem themselves. However, students may
collect data from one site and have data for comparison supplied to them.
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Internal assessment resource Science 1.12B v3 for Achievement Standard 90951
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Information could come from a variety of sources such as direct observations,
collection of experimental data, resource sheets, photos, videos, websites, and
reference texts.
You will need to include in your teaching and learning programme before
assessment: freshwater ecosystems, ecological characteristics and processes,
human impacts, use of equipment to measure environmental conditions and sample
macro-invertebrates, processing data (calculation of averages, % total organisms
present and pollution tolerance index, bar graphs), and how to use findings and
ecological ideas to make causal links between change in environmental factors and
ecological characteristics and processes and the impact these have on organisms
and the ecosystem as a whole.
Conditions
Students will carry out the fieldwork in groups of up to three students. Each student
will record their own data, and complete the rest of the work individually, in class.
Students should use the templates provided to record their fieldwork. Modify the
templates to suit the sites investigated.
Collect recorded data from students as they leave the field and return it to them to
complete the rest of the task.
Students will need about six hours to complete the task; two hours for each part.
Resource requirements
Suitable equipment for sampling in the field includes: black disc apparatus,
thermometer, pH probe or paper, stop watch, 10m tape, metre rulers, orange, nets,
buckets, bug sorting boxes or trays, identification sheets.
You need to provide students with a means of correctly identifying the types of
organisms they are likely to find. Examples include A Photographic Guide to
Freshwater Invertebrates of New Zealand (Otago Regional Council, 1997) and the
bug identification chart found in the bug box of the Stream Sense Kit produced by
Environment Waikato.
Provide access to resources to assist students to discuss the distribution of the
organisms with reference to environmental factors and the biology of the organism.
Additional information
None.
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Internal assessment resource Science 1.12B v3 for Achievement Standard 90951
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Internal Assessment Resource
Achievement Standard Science 1.12: Investigate the biological
impact of an event on a New Zealand ecosystem
Resource reference: Science 1.12B v3
Resource title: Freshwater Ecosystem
Credits: 4
Achievement
Investigate the biological
impact of an event on a
New Zealand ecosystem.
Achievement with Merit
Investigate, in depth, the
biological impact of an event
on a New Zealand
ecosystem.
Achievement with
Excellence
Investigate, comprehensively,
the biological impact of an
event on a New Zealand
ecosystem.
Student instructions
Introduction
This assessment task requires you to investigate in two areas of the freshwater
ecosystem the biological impact of human action on water quality and ecological
characteristics, such as the variety of organisms and their distribution pattern.
You will be directed to two different areas of the freshwater ecosystem from which
you will collect data. You will analyse the data, identify changes in environmental
factors and how these changes might affect the diversity and distribution of
organisms within the freshwater ecosystem, and write a report about this human
impact on the ecosystem.
You will work in small groups to collect your data. However, you will work individually
to record the data, collate and process it, and write your report.
You will have approximately six hours of class time to complete this task: about two
hours for each part.
Teacher note: Adapt the task and time allocations if students are supplied with
some or all of the data, and carry out minimal or no sampling themselves.
You will be assessed on how well you are able to investigate the impact of your
chosen human action on the freshwater ecosystem.
Task
Investigate the impact of human action on two separate parts of the freshwater
ecosystem.
Complete all parts of this task. See Student Resource A for further guidance.
Decide on the focus of your investigation
Choose two separate areas of the freshwater ecosystem and a human action or event(s).
Teacher note: You could choose these for the students.
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Collect field data
Collect field data from the two areas of the freshwater ecosystem. Both areas will
have features in common, but a human action and/or event(s) has affected one.
Before you start collecting the data, draw a sketch map of the area and complete a
survey of the freshwater ecosystem. An example survey you might use or adapt is
provided in Student Resource B.
Teacher note: Provide instructions for making a sketch map of each area, e.g.
include an approximate scale, vegetation on stream edge, large boulders, areas
of slow and fast moving water, any plants in the stream, etc.
Create a data-recording sheet.
Collect data on the environmental factors present in each area of the freshwater
ecosystem.
Teacher note: Add instructions about how you want students to collect the data.
Collect data on the macro-invertebrates present in each area of the freshwater
ecosystem. Example strategies are provided in Student Resource C.
Use your data-recording sheets to record the collected data.
Teacher note: Provide students with examples of data sheets, and instructions
on how to carry out the sampling. You could use or adapt Student Resource D.
Hand in your recorded data to your teacher once your fieldwork is completed. Your
teacher will return it to you when you begin the rest of the task, back in class.
Collate and process the data
Prepare a table to record the similarities and differences in the environmental factors
in the two areas of the freshwater ecosystem. For some factors, averages for each
area may have to be calculated.
Teacher note: Insert factors you want your students to investigate, e.g. water
clarity, temperature, pH.
Process the data and information you collected from the two areas of the freshwater
ecosystem.
Annotate any diagrams or photographs with supplementary notes.
Use your findings and observations to identify differences (changes) in environmental
factors between sites, and link them to the events and actions that might have
caused them. This will help you to draw conclusions in your report.
Report
Working individually, write a report on the impact of the human action on the
ecological characteristics of organisms in the freshwater ecosystem, e.g. distribution
pattern, density, or diversity.
Use your collated and processed observations and findings, and biological ideas
about ecosystems to develop your report.
Describe your observations and findings, identify differences in the environmental
factors of the two areas, and describe how the differences might affect the organisms
within the freshwater ecosystem.
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Internal assessment resource Science 1.12B v3 for Achievement Standard 90951
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Discuss the impact of different environmental factors you measured on the ecological
characteristic or process in the two areas, and the implications for the freshwater
ecosystem as a whole.
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Internal assessment resource Science 1.12B v3 for Achievement Standard 90951
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Student Resource A: Further guidance
Choosing your areas
Make sure you choose one area that has been affected by a significant human
impact or event, and one area that is relatively unchanged.
Use the unaffected area to help you identify and compare the changes in
environmental factors in the affected area, and the effects on the organisms within it.
For both areas:

identify the factors the areas have in common

identify the human action(s) or event(s) that have made an impact on one area
and have caused change in the environment within that area

collect field data that will identify how the change has affected organisms within
the freshwater ecosystem.
Data-recording sheet
Create a data-recording sheet with spaces for:

your name and an identification of the area

describing events or actions that have affected the area

identifying environmental factors

noting species counts

notes, observations, and/or drawings.
Field Data
Collect data on the specific ecological characteristic or process you are investigating,
e.g. food chains/webs, variety of organisms, nutrient cycles, water cycle, energy flow,
interrelationships (predation, parasitism, mutualism), density, distribution pattern, key
species of the organisms (plants and animals) present in each area.
Focus sheet/summary table
You will need at least three columns: one for each separate area, and one for
features in common.
Use at least three rows for listing: environmental factors, impacts on organisms
(including competition between species), and implications for the freshwater
ecosystem.
Processing your data
For each area of the freshwater ecosystem, calculate the percentage of the total
present for each macro-invertebrate.
To do this, divide the number of macro-invertebrates in the area by the total number
of macro-invertebrates found in that area.
Example:
% mayflies =
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number of mayflies found
total number of macro-invertebrates
x 100
Record this information in a table and draw a bar graph to compare the data from
each of the two areas.
Calculate the pollution tolerance index for each area and determine the water quality
of each area.
The pollution tolerance index (PTI) uses indicator organisms and their tolerance to
pollution (called a sensitivity score) to give an assessment of water quality.
To calculate the pollution tolerance index for each area, multiply the number of types
of organisms in each tolerance level by their sensitivity score (4, 3, 2 or 1).
Sensitivity scores are provided in Student Resource D.
Example:
In a sample that contains mayflies (tolerance score 4),
stoneflies (tolerance score 4), caddis flies (tolerance score 3)
and some dipteral (tolerance score 1), the calculation would
be:
2 x 4 (2 different types of organisms, each with tolerance
scores of 4 i.e. mayflies and stoneflies)
+ 1 x 3 (1 type of organism with a tolerance score of 3 i.e.
caddis flies)
+ 1 x 1 (1 type of organism with a tolerance score of 1 i.e.
dipteral)
PTI =
(2 x 4) + (1 x 3) + (1 x 1) = 8 + 3 + 1 = 12
Now compare your calculated pollution tolerance index (PTI) with this scale:
PTI value
Water quality rating
23 and above
Excellent
17–22
Good
11–16
Fair
10 or less
Poor
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Internal assessment resource Science 1.12B v3 for Achievement Standard 90951
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Student Resource B: Stream survey – environmental factors
Stream name: _____________________________
What plants are present close to or on the stream bank?

Trees


Shrubs
Grass

Other ground cover
Name the dominant plant for the following:
(a) trees/shrubs
(b) ground cover
Do the plants help prevent erosion of the stream bank?


Yes
No
What plants are present in the stream?

Rooted plants

Free-floating plants

Algae
Assess the amount of algae in the stream using the following scale


1 = None obvious
4 = Abundant algae


2 = Rocks slippery

3 = Algae
5 = Excessive algae
(>80% cover by filamentous algae)
What is the stream bottom (substrate) made up of?


1
Sand
Bedrock


Gravel

Cobble1
Mud
A cobble has a breadth of between 12.5 cm and 26.5 cm.
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What is the land surrounding the stream used for?




Residential, e.g. houses
Crops
Industrial, e.g. factories
Recreational, e.g. parks




Forestry
Grazing
Commercial, e.g. town, shops
Other
How has the stream environment been altered by humans?





No alteration
Drains, e.g. stormwater
Bridges
Roads/tracks




Rubbish/litter
Stock access
Planting of stream banks
Other
Fences
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Internal assessment resource Science 1.12B v3 for Achievement Standard 90951
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Student Resource C: Data collection strategies
Follow the instructions carefully for each test and record your results in a table.
Tests
Water clarity:

Use the black disc apparatus and take readings in three locations in the stream.
Temperature:

Use the thermometer and take readings in three locations in the stream.
pH:

Use the pH paper provided and take readings in three locations in the stream.
Stream speed:

Measure 10 metres of the stream in an area that is fairly straight.

A few metres above the start point, drop an orange into the middle of the stream.

Start the stopwatch as the orange passes the beginning of the 10 metres.

Stop timing as the orange passes the end of the 10 metres.

Repeat the measurement for three trials and record the times in the data table.

Calculate average speed.
Average speed = distance travelled (m) x correction factor
Average time (s)
Please note: The correction factor for an orange is 0.8.
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Student Resource D: Sampling the macro-invertebrates
Carry out a biological survey of the range and number of the macro-invertebrates for
each area by catching and sorting as many macro-invertebrates as possible from
your sample site:

choose three to five sample sites across the stream from one bank to the other

at each site, gently stir up the substrate, carefully wipe any boulders or rocks and
catch the macro-invertebrates in a suitable net

empty the contents of the net into a bucket or tray and allow settling

use the identification sheets provided to group the macro-invertebrates

record the types and number of macro-invertebrates found in a data table like
this:
Stream name
Type of macroinvertebrate
Sensitivity
score
Stream name
Number
found
Type of macroinvertebrate
Sensitivity
score
Mayflies
4
Mayflies
4
Stoneflies
4
Stoneflies
4
Caddis flies
3
Caddis flies
3
Beetles
3
Beetles
3
Dobson flies
3
Dobson flies
3
Damsel flies
3
Damsel flies
3
Dragonflies
3
Dragonflies
3
Hemiptera
2
Hemiptera
2
Crustaceans
2
Crustaceans
2
Snails
2
Snails
2
Worms
1
Worms
1
Midges
1
Midges
1
Totals
This resource is copyright © Crown 2015
Number
found
Totals
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Internal assessment resource Science 1.12B v3 for Achievement Standard 90951
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Assessment schedule: Science 90951 Freshwater Ecosystem
Evidence/Judgements for Achievement
Evidence/Judgements for Achievement
with Merit
Evidence/Judgements for Achievement with Excellence
The student investigates the biological
impact of an event on a New Zealand
ecosystem.
The student:
 describes observations or findings about
one human impact (urbanisation or
pollution) in two areas of the freshwater
ecosystem
 uses these findings to identify a change
in at least two environmental factors, and
how those changes might affect
organisms within the ecosystem in
relation to one ecosystem
characteristic/process (species diversity
or distribution pattern).
For example (partial sample):
Area A speed is 4 m/s and area B is 0.5 m/s.
PTI for area A good and poor for area B.
Water temperature was higher where there is
no vegetation covering the banks. pH was
higher in the area affected by lime fertiliser.
How changes in environmental factors affect
organisms:
Mayflies can’t live in area B with the poor
water quality. Snails and worms can live in
area B with higher levels of pollution/lower
water quality.
The student investigates, in depth, the
biological impact of an event on a New
Zealand ecosystem.
The student:
 explains observations or findings about
one human impact (urbanisation or
pollution) in two areas of the freshwater
ecosystem
 uses these findings to identify a change in
at least two environmental factors, and
how those changes might affect organisms
within the freshwater ecosystem in relation
to one ecosystem characteristic/process
(species diversity or distribution pattern)
 uses these findings and biological ideas to
make causal links between at least two
changed environmental factors and one
ecosystem characteristic/process (species
diversity OR distribution pattern)
 uses these links to explain the impact on
organisms, or implications for the
freshwater ecosystem as a whole.
For example (partial sample, distribution):
Trout are found only in the rural area, as they
cannot tolerate higher water temperature due
to its lower oxygen concentration.
The student investigates, comprehensively, the biological
impact of an event on a New Zealand ecosystem.
The student:
 explains observations or findings about one human impact
(urbanisation or pollution) in two areas of the freshwater
ecosystem
 uses these findings to identify a change in at least two
environmental factors, and how those changes might affect
organisms within the freshwater ecosystem in relation to
one ecosystem characteristic/process (species diversity or
distribution pattern)
 uses these findings and biological ideas to make significant
causal links between at least two changed environmental
factors and one ecosystem characteristic/process (species
diversity or distribution)
 uses these links to discuss the impact on organisms and
the implications for the freshwater ecosystem as a whole.
This discussion may involve elaborating, applying,
justifying, relating, evaluating, comparing and contrasting,
and analysing.
For example (partial sample, distribution):
Our results show that more species, including trout, are found
in the rural area where high vegetation covers the banks.
The trees on the banks shade the water to give trout the cool
water temperatures they need because of its higher oxygen
concentration.
Other species such as mayfly cannot survive in the poor quality
water in the urban area. This means that the diversity of the
freshwater ecosystem will be reduced in the urban area.
Final grades will be decided using professional judgement based on a holistic examination of the evidence provided against the criteria in the
Achievement Standard.
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